Method of butt-sealing incandescent electric lamps



Jan. 21, 1936. M; E MCGQWAN I 2,028,342

METHOD OF BUTT SEALING INCANDESCENT ELECTRIC LAMPS Filed Jan. 18, 1934 2 Sheets-Sheet 1 ,INVENTOR M E. M6 GOh/A V ATTORNEY Jan .21, 1936. Y a. E. mGQw'AN 2,028,342

METHOD OF BUTT SEALING I NCANDES CEN T ELECTRIC LAMPS Filed Jan. 18 1934 2 Sheets-Sheet 2 I'NVENTOR ME. maevwsw ATTORNEY Patented Jan. 21, 1936 METHOD OF BUTT-SEALING lNCANDES CENT ELECTRIC LAMPS it Michael E. McGowan, Bloomfield, N. 1., assignor to Westinghouse Lamp Company, a corporation of Pennsylvania Application "January 18, 1934. Serial No. 707.078 9 Claims. (01. 49-78) a bulb neck in combination with means" for formingthe plastic edge to provide definitelypo- This invention relates to electric incandescent lamps and relates more particularly to a device v and method of sealing lead wires in the wall of a lamp bulb of the miniature type.

In the manufacture of incandescent electric lamps of the'miniature type such as Christmas tree lamps as well as certain forms-of precision lamps as used for motor vehicles, it is the practice to provide whatis termed a mount consist-- ing of a filament having its terminals securedto lead wires. The lead wires areheld in-sp'aced relation by a glass bead and the free ends of the leads are bent at a point intermediate the bead and the ends of the leads at right angles and in opposite directions i The mount so formed is disposed with the filament projecting into a bulb held with the open end-or neck up. The extending portions of the lead wires rest upon the edge of thelneckand serve to support the filament inthe position at which itis secured. An exhaust'tube is then moved so that the edge of one end is disposed in contact or inclose spaced relation to the extended leads and the neck and end of the exhaust tube are heated to consolidate them by fusion which also seals the leads through the wall or neck'of the bulb. I 1

This practice, which is termed butt-sealing, has certain defects as for example, it is necessary that the bulb neck have a uniform edge I which is difficult to obtain owingto the' fact that the neck must be out to provide such an edge.

Furthermore, the edge of the neck may be a greater or lesser distance fromthe desired light center of the bulb so that when the mount has been sealed-in, the filament will not always be in the position desired along the longitudinal axis .of the bulb or it may be out of'position laterally.

It is an object of the present invention,therefore, to provide a method of controlling the position of a mount within a bulb when the mount leads are sealed through the bulb wall and to shape the bulb neck edge for union with an exhaust tube. l

Another object of the invention is to provide a method of butt-sealing which comprises forming in the neck of a bulb a depression or seat a predetermined distance from a point along the longitudinal axis of the bulb to receive the lead wires of a mount to position the light source of the mount when the lead wires are sealed through the bulb wall upon a consolidation of an exhaust tube with the bulb neck.

Another object of the invention is to provide means for heating to render plastic the'edge of tioned to be sealed to a sitioned portions to receive le ad wires of a mount.

Other objects and advantages of the invention will be more clearly underst ood by reference to the following description together with the accompanying drawings iniwhich v Fig. 1 is a side view of a bulb supported to have the neck portion shapedin accordance withgthe present invention.

Fig. '2 is a viewshowing the shaping member in position to shape the bulb neck.

Fig, 3 shows the shaping with the bulb neck."

member in contact Fig. 4 shows theshaping memberiremoved and notches formed in the bulb neckl Fig. 5- shows a mount being positioned the notches. I

Fig. 6 shows an 'exhausttube ready to be moved to position to be sealed-to th e bulb neck.

Fig. 7 shows the operation of sealingan ex- .hausttube to the bulb neck.

- Fig 8 shows a .bulbwith the-.mount sealed therein.

a shaping operation.

Fig. 12 shows an exhaust tube ready to be posibulb neck, and

Fig.13shows a mount with thelead wires bent to seat in the notchesv formed by a shaping tool.

As shown inFig. l a bulb suitable support I l manufactured under; ordinary conditions.

mountsuch as shown in Fig.

I0 may be held in a The bulb 0 is shown as it is 5 is positioned with 1 v the laterally extending lead wires 12 and-l3 ofa on the edge 14, of t. or lightsource l5 hangs downwardly .within' the bulba'nd is sup-.

ported by the leads I2 and I3 preparatory to the union between the bulb neck and an exhaust tube.. An exhaust tube is then so disposed that an edge is in contact with or close to the edge 14 of the bulb." Fir es are then directed to heat and fuse the edges of the exhaust tube and bulb neck at which time the lead wires are sealed throughthe result ing wall of the bulb.

This method of butt-sealing an exhaust tube to a bulb is commonly used in the lamp art and is more clearly shown in Patent. No. 1,742,153 issued December 31-, 1929 for Sealing machine for incandescent lamps and similar articles.

When practicing the me thod ,as heretofore employed, certain difliculties existed in maintaining the position of the filament uniform with respect to a given point within the bulb. Owing to the certain bulb manufacturing operations it is difficult to obtain bulbs with the edges in a' definite plane transverse to the axis of the bulb 'and such edges are often irregular. Thus, when the lead wires of a mount are positioned across the bulb edge the position of the filament can'- not be held to an accurate definite position.

.The present invention provides means including a forming tool 20 arranged tomove along the longitudinal axis of the bulb toward and away from a bulb neck It. The tool 25) may have a flange 22 and a centering tip 2| proportioned to slidably fit the interior surface of the bulb neck. The flange may be provided with oppositely disposed U- or Vshaped bosses or presser lugs 23 radially disposed on the under surface of the flange 22.

The edge M of the bulb is then subjected to heat from any suitable source as gas flames 24 and when the edge J4 has been softened, the tool 20 is moved to bring the flange 22 against the plastic edge so that the forming lugs 23 make impressions 25 of U- or V-shape as shown in Fig. 4. ,The tool 20 maybe moved to compress the softened glass so that the seats at the bottoms of the grooves or depressions will be a predetermined distance from a pointalong the axis of the bulb as for example the distance X indicated in Fig. 4 may be positively maintained thus insuring the light source of being disposed at a definite position in a bulb and making it possible to manufacture bulbs in large volume with each filament similarly positioned.

While the bulb is held by jaws 25' a mount is positioned by suitable feeding means 26 so that the lead wires l2 and I3 are disposed in the slots or notches 25. Since the distance between the filament and the laterally positioned portions of the leads can be held uniform, the position of the filament will be controlled by the position of the seats formed by the tool 20. An exhaust tube 26 is then moved so that an end 21 is adjacent to the edge H! of the bulb and fires'28 are directed against the opposing tubular glass portion to fuse them and seal the lead wires through the wall.

After the exhaust tube is sealed to the bulb and before the glass has hardened, the bulb and tube are moved relative to each other to cause a constricted portion to form in the exhaust tube to facilitate a subsequent tipping-off operation after the bulb has been exhausted. The various operations directed to the shaping of the bulbneck may, obviously, be performed on a machine such as shown in the above mentioned patent including a conveyor which may move the bulb from one position to another for the shaping operations and these operations may be added to machines now employed for sealing exhaust tubes to bulbs.

The tool 20, with the centering portion 2|, causes the material displaced at the edge I4 of the bulb to extend outwardly, as shown in Figs. 3 to 8. If desirable, however, as shown in Figs. 10 to 12, a tool 30 may be employed having a hood 3| to enclose the end of the bulb neck during the forming operation. Within the hood may be provided a pair of bosses or a cross bar 32 of a V-shape so arranged that when the tool 30 is moved to engage theplastic neck portion of the bulb the cross bar will form V-shaped notches 33 but the displaced material will be disposed within the neck of the bulb and the outside surface of the neck will remain smooth and cylindrical.

The hood 3| of the tool 30 may be provided with a central pin 30 which serves to maintain the required diameter of the hole in the neck. The hood 3| in conjunction with the pin 30 makes it possible to confine the plastic glass and provide a fiat edge in a plane transverse to the longitudinal axis of the bulb and to so dispose the surface of the edge that the lead wires I2 and 3 will lie flat. The accurate disposition of the filament in a predetermined position within the bulb is thus readily attained. The pin 31! may be so proportioned that it forms a hole of a diameter slightly greater than the distance between opposite outer surfaces of the portions of the. lead wires which extend through the neck. By thus controlling the size of the aperture in the neck to fit the said portions of the lead wires the filament may be more effectively centralized.

By reason of the present invention it is possible to improve the quality of lamps in that the desired accuracy and uniformity of light center is possible without an appreciable increase in cost since the'present method and means may easily and economically be applied to existing equipment.

Although a preferred em odiment of the present invention is shown and described herein it is obvious that modifications may be made therein without departing from the spirit and scope thereof as pointed out in the appended claims.

What is claimed is:

1. The method of positioning the filament of a lamp mount in a given position within a bulb which comprises heating a bulb neck until plastic, forming surfaces on the neck in a predetermined relation to a given point in the bulb, positioning the lead wires of a mount on said surfaces and butt-sealing an exhaust tube on said bulb neck.

2. The method of positioning the filament of a lamp mount in a given position within a bulb which comprises heating a bulb neck until plastic, forming notches in the bulb neck to receive the lead wires of a mount and butt-sealing an exhaust tube to the bulb neck.

3. The method of butt-sealing the component parts of an incandescent electric lamp, which comprises positioning a bulb with the neck disposed uppermost, heating the neck until plastic, forming notches in the plastic portion while controlling the displacement of the plastic material, disposing the lead wires of a mount in said notches and butt-sealing an exhaust tube to said bulb neck.

4. The method of butt-sealing two vitreous tubular bodies and embedding a third body in the seal thereof, which comprises displacing material on the edge of one of said bodies to provide indentations to receive the third body while controlling the fiow of displaced material, positioning said third body in said depressions and in butt-sealing to unite said two vitreous bodies.

5. The method of making incandescent electric lamps with the filament in predetermined positions which comprises forming surfaces on the bulb neck a predetermined distance from a given point in the bulb, providing a mount with laterally bent lead wires and with the distances between the bends and the filament equal to the distance between said surfaces and said pointin the bulb, positioning said mount with the lead wires disposed on said surfaces and sealing said wires in said neck.

6. A device for preparing the end of a bulb for a butt-sealing operation comprising, means for supporting a bulb, means for heating the neck 01' the bulb to render the same plastic and a presser member movable longitudinally of the bulb for compressing the bulb neck to position the surface of the edge of the said neck a predetermined distance from a point selected along the longitudinal axis of the bulb.

7. A device for preparing the end of a bulb for a butt-sealing operation comprising, means for supporting a bulb, means for heating the neck of the bulb to render the same plastic, and a presser member for compressing the bulb neck longitudinally to position the surface of the-edge of the said neck a predetermined distance from a point selected along the longitudinal axis of the bulb, said presser member having means {or forming notches across said edge to receive the lead wires of a lamp mount.

8. A device for preparing the end of a bulb for a butt-sealing operation comprising, means for supporting a bulb, means for heating the neck of the bulb to render the same plastic, a presser member for compressing the bulb neck longitudinally to position the surface of the edge of the said neck a predetermined distance from a point selected along the longitudinal axis of the bulb, said presser member having means for forming notches across said edge to receive the lead wires of a lamp mount and means for positioning a mount with the fliamentwithin said bulb and the lead wires disposed in said notches.

9. The method of butt-sealing two tubular bodies and embedding a thirdbody in the seal thereof which comprises heating and mechanically compressing to shape the edge of the one body to prepare it for attachment to the said third body, moving the first and second bodies in butt-sealing relation, heating to. render plastic adjacent portions of said 'last mentioned bodies. 0

to cause them to unite by fusion and seal said third body. 7 MICHAELE. McGOWAN. 

